Sometimes the most simple thing is the most elegant as well. Here is an Easy Release Key Ring from Lowe's for under 2 bucks. I think 1.78. Simply push the center and the two pieces come apart. The thing swivels as well. Pump with it in place or push the center and have some more room. Hope you like it.

BillS, how do you defuel your planes if you use air and pump via pressure, and how do you shut if off quickly? The Hangar 9 pump is what Jersey Modellers has on their can, so I'm just going with tried and true.

Doug